Method of making a deflection coil

ABSTRACT

Deflection coil obtained by winding a strip of foil, from which thin slices are cut after having been baked to a block, said slices being bent into a cylindrical shape.

United States Patent Tan etal.

[ 1 Sept. 5, 1972 [54] METHOD OF MAKING A DEFLECTION COIL [72] Inventors: Sing Liong Tan; Mathiis Willem Bartels; Walter Wilhelmus Degger, all of Emmasingel, Eindhoven, Netherlands [73] Assignee: U.S. Philips Corporation,

York, NY.

[22] Filed: May 20, 1971 [21] Appl. No.: 145,503

' Related U.S. Application Data [63] Continuation of Ser. No. 3,138, Jan. 15, 1970.

New

[52] U.S. Cl. ..29/605, 335/213, 336/206 [51] Int. Cl ..H0lf 7/06 [58] Field of Search...29/605; 335/210, 213; 313/75,

[56] References Cited UNITED STATES PATENTS 3,113,374 12/1963 Zack ..29/605 2,167,379 7/1939 Tolson ..313/76 2,207,777 7/1940 Blain ..335/213 3,433,705 3/1969 Cornish ..335/213 X 2,949,593 8/ 1960 Staley et a1. ..336/206 X Primary Examiner-John F. Campbell Assistant Examiner-Carl E. Hall AttorneyFrank R. Trifari [57] ABSTRACT Deflection coil obtained by winding a strip of foil, from which thin slices are cut after having been baked to a block, said slices being bent into a cylindrical shape.

7 Claims, 2 Drawing Figures PNENTEDsEP' 5 I872 fig SING LIONG TLN MATHUS W. BARTELE WALTER W.J.\DEGG R K This application is a continuation of Ser. No. 3,138, filed Jan. 15, 1970.

The present invention relates to a flat coil bent subsequent to winding into an at least partly cylindrically shaped surface for producing a magnetic deflection field in a cathode ray tube. Around the neck of the tube usually two such coils are arranged for the horizontal deflection and two other coils for the vertical deflection pairwise in diametrically opposite positions. By winding the coils in a flat shape and by subsequently bending them into a cylindrical form, the winding operation is simplified.

Deflection coils for color television, when a separate cathode-ray tube is employed for each of the three fundamental colors, have to meet severe requirements with a view to avoiding display errors in connection with the similarity of the deflection coils to be used in one apparatus, for example, for the horizontal deflection. It is known to form a flat deflection coil from a plurality of rectangular coil portions of progressive size fitting one in the other and to bend the set of coils baked into a fairly rigid unit into the required semicylindrical shape. Practically speaking, it is not possible to wind completely regularly the coil parts wound from conventional wire and, moreover, the coils having little resistance to deformation are subjected during bending to secondary deformations so that in this way the three accurately identical coil pairs cannot be obtained.

An object of the invention is to provide a method and construction in which it is indeed possible to wind uniform deflection coils.

The coil according to the invention is characterized in that the coil is spiralized from a metal foil provided on at least one side with an insulating layer and is reduced by a cutting operation to a thickness which permits bending.

It is known to wind coils for electromagnets pairwise from a metal foil. However, in this case we are dealing with round coils of considerable thickness in the axial direction which are not bent after winding.

The invention will be described more fully with reference to the accompanying drawing, in which FIG. 1 illustrates a stage in the manufacture of a coil in accordance with the invention, and

FIG. 2 is a perspective view of this coil in its final shape.

FIG. 1 shows a body 1 wound from a copper foil, of a thickness of, for example, 0.1 mm and of a width of a few centimeters, coated on one side with a preferably thermoplastic, insulating lacquer, on a mandril of rectangular or other, for example, trapezoidal cross section (not shown). After winding the body 1 is baked to a rigid, block-shaped unit, from which a flat coil 5 of not more than 2 mm, for example, 0.5 mm thickness is cut in known manner on a lathe by means of a chisel, for example, along the broken line of FIG. 1. As a result of this cutting operation the edges of the foil turns will, in general, be welded together and be relatively shortcircuited. These short-circuits may be eliminated by etching the coil in known manner. The flat coil 5 can then be bent, thanks to the small thickness of less than 2 mm, in an appropriate jig into the semi-cylindrical 2 shape shown in FIG. 2. The form of the coil matches the ha e of the tube for x a t 7 (shofivnin FIG. 2 in broken fin gs fiii wh fi iig c ll is intended to serve as a deflection coil, in this case for the horizontal deflection.

The horizontal deflection coil set comprises a second coil (not shown for the sake of clarity) which is located diametrically opposite the coil 5 and which has to be of optimum identical shape with the coil 5 in order to prevent the deflection field from introducing errors in reproduction. By cutting the two coils of the pair and those of two further pairs from the same body 1 and by providing equal thicknesses of the coils, the required similarity of all coils for the. horizontal deflection in a color television camera can be obtained without additional costs. The same applies of course to the vertical deflection coils.

A still more accurate similarity of the coils can be obtained by embedding each of the coil pairs, after bending, in a synthetic resin so that the two diametrically opposite coils with the synthetic resin form a hollow cylinder, which is accurately machined on the lathe to a predetermined inner and outer size, after which the metal surfaces are etched. This construction may be employed advantageously when each of the coils is formed in known manner from a plurality of separate parts of progressive sizes fitting one in the other to form a flat unit. This also applies to the case in which the coils have a partially conical shape.

What is claimed is:

l. A method of fabricating a thin flexible coil having at least a partially cylindrical shaped surface from a conductive metal foil strip having a layer of insulating material on one surface thereof which comprises, spirally winding said foil strip to form a multilayer coil body with an aperture therein, heating said body to form a rigid block, cutting off one or more thin flat coils from said block of a thickness which permits the severed flat coil to be easily bent into shape, etching the edges of the severed flat coil, and bending said flat coil so as to form a multi-tum coil having at least a partially cylindrical shaped surface adapted for mounting on the neck of a cathode ray tube or the like.

2. The method of claim 1 wherein said cutting operation is preformed along a plane parallel to the plane of the aperture so as to cut off a flat aperture coil of a thickness less than two millimeters.

3. The method of claim 1 including the further step of encapsulating a pair of said bent coils in an insulating material to form a hollow cylinder with the two coils diametrically opposed and longitudinally extending parallel to the cylinder axis.

4. The method of claim 3 wherein the insulating material is comprised of a synthetic resin.

5. The method of claim 3 comprising the further step of reaming the inner surface of said cylinder to a predetermined size.

6. The method of claim 2 wherein the foil strip is wound about a rectangular mandril and said insulating material comprises a thermoplastic insulating lacquer.

7. The method of claim 6 wherein said foil strip is composed of copper foil and wherein said bending step is performed on a cylindrical jig.

32 33 I UNITED STATES PATENT OFFICE CER'IIFICATE 0F CORRECTEON P t 8, 394 Dated September 5, 1972 Inventor.(s) SING LIONG "IAN ET AL a It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE TITLE PAGE below "Appl. No. insert as follows:

Foreign Application Priority Data January 17, 1969 notch. .6900789 Signed and sealed this 20th day of November 1973.

(SEAL) Attest:

EDWARD M.FLET0MER,JR. RENE D. TEGTMEYER Attesting- Officer Acting Gommissioner of Patents P9293 UNITED STATES PATENT OFFICE QERTIFECATE 01* (10 ECTEON pa 3,688,394 k Dated September 5, 1972 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE TITLE PAE below "Appl. No. insert as follows:

Foreign Application Priority Data January 17, 1969 Dutch. .6900789 Signed and sealed this 20th day of November 1973.

(SEAL) Attest:

EDWARD M.FLE2TCI1ER,JR. RENE D. TEGTPLEXER Acting Qommissioner of Patents Attesting; Officer 

1. A method of fabricating a thin flexible coil having at least a partially cylindrical shaped surface from a conductive metal foil strip having a layer of insulating material on one surface thereof which comprises, spirally winding said foil strip to form a multilayer coil body with an aperture therein, heating said body to form a rigid block, cutting off one or more thin flat coils from said block of a thickness which permits the severed flat coil to be easily bent into shape, etching the edges of the severed flat coil, and bending said flat coil so as to form a multi-turn coil having at least a partially cylindrical shaped surface adapted for mounting on the neck of a cathode ray tube or the like.
 2. The method of claim 1 wherein said cutting operation is preformed along a plane parallel to the plane of the aperture so as to cut off a flat aperture coil of a thickness less than two millimeters.
 3. The method of claim 1 including the further step of encapsulating a pair of said bent coils in an insulating material to form a hollow cylinder with the two coils diametrically opposed and longitudinally extending parallel to the cylinder axis.
 4. The method of claim 3 wherein the insulating material is comprised of a synthetic resin.
 5. The method of claim 3 comprising the further step of reaming the inner surface of said cylinder to a predetermined size.
 6. The method of claim 2 wherein the foil strip is wound about a rectangular mandril and said insulating material comprises a thermoplastic insulating lacquer.
 7. The method of claim 6 wherein said foil strip is composed of copper foil and wherein said bending step is performed on a cylindrical jig. 